In current technology, lyophilization has resolved several problems in the food and pharmaceutical industries. For instance, lyophilized substances are currently being effectively utilized as the basis for injectable compounds, such as human growth hormones (HGHs), biologicals, vaccines, immunomodulators, medicaments, and the like. Lyophilization involves the rapid freezing of a substance at a very low temperature followed by rapid dehydration by sublimation in a high vacuum. Lyophilization processes can reduce or eliminate the need for difficult storage and handling arrangements and may provide a pathway to a product with a favorable shelf life. In addition to its role in making certain injectable medicaments feasible, lyophilization is being used to find alternatives to a variety of dry-powder-filled products that have undesirable processing and/or product characteristics. Although these powder-filled products are less expensive to produce, their manufacture can involve challenges in processing safety (powder control), uniformity (blending), aesthetics, inspectability, reconstitutability, stability (residual moisture and solvent control), and particulate control. Regulatory and industry professionals recognize that these characteristics are better controlled or overcome with the development of lyophilized forms of such products.
A prior art lyophilization process utilizes a lyophilization chamber having shelves suitable for accommodating at least one chemically inert container (e.g., a glass vial), and, in essence, consists of a filling stage, a freezing stage, a primary drying stage, and a secondary drying stage. During the filling stage a predetermined amount of fluid substance or formulation is provided to the container. During the freezing stage the formulation is cooled. Pure crystalline ice forms from the fluid substance, thereby resulting in a freeze concentration of the fluid remainder to a more viscous state that inhibits further crystallization. Ultimately, this highly concentrated and viscous solution solidifies, yielding an amorphous, crystalline, or combined amorphous-crystalline phase. During the primary drying stage, the ice formed during the previous freezing stage is removed by sublimation at sub-ambient temperatures under vacuum. This stage is traditionally carried out at chamber pressures of 40-400 Torr and shelf temperatures ranging from about −30° C. to about +10° C. Throughout this stage, the substance is maintained in the solid state below the collapse temperature of the substance in order to dry the substance with retention of the structure established during the freezing stage. The collapse temperature may be, for example, the glass transition temperature (Tg) in the case of amorphous substances or the eutectic temperature (Te) for crystalline substances. During the secondary drying stage, the relatively small amount of bound water remaining in the matrix is removed by desorption. During this stage, the temperature of the shelf and substance are increased to promote adequate desorption rates and achieve the desired residual moisture.
Typical lyophilization processes require sophisticated mechanical equipment with advanced data acquisition and control systems. For instance, to fill conventional lyophilization containers with sterile substances or compounds to be lyophilized, it is typically necessary to sterilize the unassembled components of the lyophilization container, such as by autoclaving the components and/or exposing the components to gamma radiation. The sterilized components then must be filled and assembled in an aseptic isolator of a sterile filling machine. In some cases, the sterilized components are contained within multiple sealed bags or other sterile enclosures for transportation to the sterile filling machine. In other cases, the sterilization equipment is located at the entry to the sterile filling machine.
One drawback associated with prior art lyophilization cap/container assemblies, and processes and equipment for lyophilization, is that the filling process in combination with the lyophilization process is time consuming, and such processes and equipment can be costly. Further, the relatively complex nature of the filling/lyophilization processes and equipment can lead to more defectively filled containers than otherwise desired. For example, typically there are at least as many sources of failure as there are components. In many cases, there are complex assembly machines for assembling the lyophilization containers that are located within the aseptic area of the filling machine that must be maintained sterile. This type of machinery can be a significant source of unwanted particles or contaminants. Further, isolators are required to maintain sterile air within the barrier enclosure. In closed barrier systems, convection flow is inevitable and thus laminar flow, or substantially laminar flow, cannot be achieved. When operation of an isolator is stopped, a media fill test may have to be performed which can last for several, if not many days, and can lead to repeated interruptions and significant reductions in production output for the pharmaceutical or other product manufacturer that is using the equipment. In order to address such production issues, government-imposed regulations are becoming increasingly sophisticated and are further increasing the cost of already-expensive isolators and like filling equipment. On the other hand, governmental price controls for injectables discourage such major financial investments. Accordingly, there is a concern that fewer companies will be able to afford such increasing levels of investment in sterile filling machines, thus further reducing competition in the marketplace.
Another drawback associated with known lyophilization containers, and processes and equipment for lyophilization, is that during the lyophilization process it is necessary to allow communication between the contents of the container and the ambient atmosphere, which, in effect, increases the vulnerability of the container contents to compromise. Notwithstanding this increased vulnerability, the atmospheric communication is essential in order that moisture may be appropriately vented as needed during the lyophilization process. Conventionally, this venting requirement has been addressed by utilizing a stopper that has an extended lower portion with one or more vent openings therein, and by seating such stopper only partially in the container after the filling stage so that the vent openings of the lower portion expose the contents of the container to the ambient atmosphere. Moisture removed from the contents of the container during lyophilization may thus escape through the vent openings. As a general method of closing the container, shelves in a lyophilization chamber vertically move together to press the stopper down into the container until the vent openings in the lower portion thereof are well inside the container, thereby preventing any further ingress and/or egress of moisture and/or air. A metal seal or crimp also may be used to securely hold the rubber stopper to the container and prevent any unwanted disengagement therewith. Accordingly, conventional lyophilization container/stopper assemblies and related venting techniques, although suitable to provide the required venting, fail to address the desirability of ensuring the integrity of the contents of the lyophilization container.
A further drawback associated with the foregoing lyophilization processes and containers is that the container stoppers may stick to the shelves of the lyophilization chamber. This typically happens at the end of the lyophilization process, which may take as long as 72 hours, after the shelves have moved down to seat the stoppers in the containers. When the shelves are subsequently retracted, some stoppers may stick to the shelves, resulting in at least a small portion of the batch being lost. In extreme cases, the entire batch may be ruined, which can be costly and inefficient.
Still another drawback associated with known lyophilization containers and processes is found in the reconstitution process. As is apparent from the foregoing discussion, it is necessary to reconstitute a lyophilized substance or compound, via a suitable diluent, prior to the administration thereof. Reconstitution is typically accomplished by injecting a diluent (e.g., via a needle syringe) into a container containing the lyophilized substance. During reconstitution, the diluent often interacts with the lyophilized substance so as to cause the lyophilized substance to foam. This foaming effect can create an undesirable head space in the container such that the appropriate amount of diluent is not mixed with the substance, resulting in an improper diluent to compound ratio. This negative foaming effect necessitates waiting some length of time for the foam to subside before proceeding with the administration of the reconstituted substance. Accordingly, it would be advantageous to provide a lyophilization container that minimizes or otherwise reduces this negative foaming effect in comparison to prior art lyophilization containers.
It can be desirable for lyophilized substances to possess certain characteristics including, but not limited to, (1) long term stability, (2) short reconstitution time, (3) elegant cake appearance, (4) maintenance of original dosage characteristics upon reconstitution, including solution properties, structure and/or conformation of proteins, as well as particle-size distribution of suspensions, and (5) isotonicity upon reconstitution. Control and monitoring precision, accuracy, and reproducibility as well as product aesthetics, stability, and reconstitution characteristics are factors to be addressed in the evolution of lyophilization. Further, many substances to be lyophilized, such as antibiotics and medicaments, immunological products, substances derived from genetic engineering, high molecular weight proteins, and sophisticated peptides are very fragile, difficult to freeze, and highly sensitive to residual moisture content. Accordingly, the demand for improved lyophilization containers, processes, equipment and/or techniques for producing, in a reproducible and reliable manner, quantities, large and small, of lyophilized substances will necessarily increase.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and disadvantages of the prior art and to address the need for improved lyophilization devices, processes, equipment and/or techniques.